1. Field of the Invention
This invention relates to the field of apparatus and methods for breaking optical fibers in such manner as to achieve substantially perfect mirror-finish ends at the break.
2. Description of Prior Art
In the article by Gloge, Smith, Bisbee and Chinnock (The Bell System Technical Journal, November, 1973, pages 1579 et seq.), it is stated (page 1580) that "The range within which perfectly flat and perpendicular end faces were obtained was found to be so wide that the eventual construction of a simple hand tool for this purpose should present no problem." Nevertheless, the hand tools subsequently created by Bell Laboratories and other major companies have not been commercially practical or successful. That is to say, they have not been such that telephone repairmen, for example, can almost always make a perfect break--even while in a manhole or up a telephone pole--in a matter of seconds if at all. Furthermore, and very importantly, the prior art suggests no practical correlation between the breaker and the optical connectors.
Reference will now be made to some of the important prior-art problems which the present apparatus and method have eliminated. The following is not necessarily all inclusive, nor are the problems necessarily listed in order of importance.
Referring first to scoring, it was conventional in the prior art to lower a scoring blade delicately onto the fiber (either prior to or after tensioning of the fiber). Then, as a second operation, the blade was moved along its length sufficiently to effect scoring or nicking of the fiber. On page 1585 of the cited article, scorer pressures ranging from 1.5 to 7.5 grams are suggested. It is further there stated that the smallest scores were produced when a sharp diamond scorer was lowered onto the fiber after application of tension. A strong preference for diamond or sapphire scorers is typical of most prior art. The prior art also employs, typically, such things as counterweights and/or dashpots to achieve the desired delicate contact between scorer and fiber.
Applicant has discovered that--surprisingly--maximum scorer pressure on the glass may be made to be no factor whatever. Thus, just so long as there is enough pressure to effect scoring, the pressure may be as high as convenient and need not be measured at all. This discovery not only eliminates the need for counterweights, dashpots, measurements, etc., it makes the apparatus and method absolutely independent of orientation (upright, inverted or sideways) in that gravity is of no importance. Additionally, applicant does not require (or even desire) exotic blade material such as diamond or sapphire, having discovered that a certain type of carbide is vastly superior.
Referring next to correlation between the breaker for optical fibers and the connectors therefor, insofar as applicant is aware the prior art suggests no practical means of achieving this major result. Thus, in almost all prior art the breaking and subsequent connecting of the fibers are totally independent operations. In accordance with the present invention, the breaking and connecting apparatus and methods are such as to achieve a breakingconnecting system which not only reduces overall connection time, there being (for example) no need for adhesive, but increases the overall quality of the connection.
With reference to creation of the tension in the fiber, this has conventionally been achieved by (a) predetermined weights, or (b) special "tensator" springs the force of which does not change with distance, or (c) special frictional grips which are intended to slip at a predetermined tension value, or (d) unknown forces which require that, preferably, scoring be effected before tensioning occurs. In the preferred forms of the present apparatus and method, the fiber is clamped in a nonslip manner, tensioning is caused by an economical spring means which is unaffected by excessive grip pressure, and scoring is then performed. There thus result major improvements in the practicality of the tool.
As but one additional example of the deficiencies of the prior art, there is no practical means for insuring that all types and thicknesses of the synthetic resin coating will be removed at regions adjacent the break--this being important for achievement of optimum connections. In accordance with one embodiment of the present apparatus and method, such coating is burned off in the critical areas with no requirement for additional manipulation of the fiber, and with only a small reduction in the speed of the operation.